When someone says a system is “load sensing,” it means that it has been designed to operate at as low a flow and/or pressure as possible when no functions are actuated and is able to immediately “jump” back up to the flows and pressures necessary to do the work demanded. The advantages of this are lower total energy use (in the form of engine fuel or electricity in the prime mover), less heat created, and longer component life. As with most things in mobile hydraulics and controls, there is more than one way to accomplish this feature.

CAN J1939 is the communication network used by electronic diesel engines to transmit data about the operating conditions of the engines to the Engine Control Module (ECM). These two wires, CAN + and CAN -, are the superhighway of information for the modern engine. We use this network to transport data to other devices necessary to operate your mobile machinery.

In the mobile hydraulics world, there are many applications that require a hydrostatic pump, also known as a transmission. Most applications are centered around some sort of propulsion of a machine, but there are many others like conveyors, drills, etc. Most will drive some sort of hydraulic motor. Applications range from huge harvester combines to small walk behind mowers. Displacements of these pumps can range tremendously from just a few cc to well over 200. These types of applications are known as “closed loop”.

When many people start designing their hydraulic system, the only two factors they consider are cost and functionality. Though these are very important aspects of a systems design, it can also lead you to problems if not carefully thought out. You want your system to run correctly but you also want it to be as cost-effective as possible. Picking the correct components goes further than just what pump/motor is cheapest and fits the displacement needs. Combining the wrong product types together can potentially be harmful to your system.

I have been working in the fluid power industry over 30 years. My interaction in it has changed during that time. In my earlier years, most of my applications were done in the industrial hydraulics market. For the more recent half of my career, it has been trending more to the mobile hydraulics realm, which now represents the majority of my hydraulic applications.

Eaton has changed the design of their pressure flow compensator (load sense) for their X20 Series open loop piston pumps (220 / 420 / 620). I have had recent experience with NGC and am writing to describe some of the changes and simplify some of the technical language provided in Eaton’s Customer Bulletin.
NGC Design Upgrades and Comments
It is important to know that the Next Generation Compensator has the exact same mounting bolt pattern and screw length as the original design and is a direct mounting interchange as a service part to older X20 pumps.

Most, if not all, air conditioners on mobile equipment are driven by hydraulic motors. The one requirement is the hydraulic motor that is connected to the air condition compressor needs turn at a constant RPM regardless of engine RPM.
3 Ways to Control Mobile Hydraulic A/C Compressor RPM
There are three common ways to accomplish this feat. Two are OK but one shines above the rest.

Hydraulic components are getting smaller, less expensive, and more complicated as machining processes and manufacturing efficiency continue to improve. For flow dividers, what used to require a bulky pair of mechanically linked gear motors has been shrunken down to a cartridge valve.